in Germany we always judge a plant in May because only then you see if a plant survived. It looks the same to you. What a shame to see all the beauties dying. But if you live in zone 4 it's always critical.

As the winter in Germany was not to strong nearly all my plants survived, only two which where already close to death because of damages by some animals died finally.

The hybrids from Tim did great here in my area, a few are still small seedlings, waiting to be released to the wilderness.